Time stamp



4 Sheets-Sheet l c. D. LAKE TIME STAMP Filed Oct. 28, 1953 INVENTOR flwwog ATTQRNEY m we "m m I ET wax June 4,- 1935.

June 4, 1935.

c. D. LAKE ,003,787

TIME STAMP Filed Oct. 28, I933 '4 Sheets-Sheet 2 rllllI INVENTOR $0; 14% BY ATTORNEY June 4, 1935. Q Q LAKE 2,003,787

TIME STAMP Filed Oct. 2a, 1955 4 Sheets-Sheet. 4'

J 1 90 -"47 '00 |NVENTOR 89 H'T T BY ATTORNEY E36 WA Patented June 4, 1935 UNITED STATES PATENT OFFICE TIME STAMP Clair D. Lake, Binghamton, N. Y., assignor to International Business Machines Corporation, New York, N. Y., a corporation of New York Application October 28, 1933, Serial No. 695,647

14 Claims. (01. 101-287) This invention relates to time stamps in genclaims or will be apparent from a study of the oral and, more particularly, to time stamps description, claims and the accompanying which are operated, and/or controlled by elecdrawings: tricity. In the drawings :1 V

The broad object of the invention is to gen- Fig. l is a vertical longitudinal section through 5 erally' improve time stamps by providing opera time stamp embodying the present invention; ating and controlling mechanisms which enable Fig. 2 is a vertical transverse section on the a more uniform impression to be had and line 2-2 in Fig. 1; 7 wh operation is r r li bl Figs. 3, 4, and 5 are similar views taken on A general object is to provide novel controle lines .v nd 5-5, p ctively, in 10 ling and operating means for electrically 0011- trolled time stamps which means are more or 61 a detail View Of Certain fl in less independent of transient phenomena or pe- Fig. 1.; riodically changing conditions of the supply line Fig. 7 is a view showing a modification;

1,5 such as variations in potential. For example, 3 s a u t d a a when alternating current must be used to oper- The time Stamp s of t e same eneral type ate the clamp the novelmeans is adapted to be as the one described in Patent N0. 1,798,583 more or less independent of the point in the t d M y 1930 Bishop and alternating current wave at which the circuit is sprecker- The entire time Stamp iS un e g closed to bring about an operation of the stamp. p a ba Cas which has lugs ll D- 29 A specific object is to provide an operating porting a frame casting l2. This frame casting mechanism for time stamps which includes a pp at itS-Tight-hand d (Figsp spring-operated toggle as the means for opering d which y be Similar o the One @18- ating the impression taking device. scribed in the above patent. The frame I2 is Another specific object is to provide an operenclosed by the lower half H of a two part hous- 25 ating mechanism for time stamps which is ren C the pp half M of whic enleased for operation by means of a'relatively OSQS the printing heade atter has not low power electromagnet or solenoid. been shown as the present invention relates to A further specificobject is to provide a time means for operating and controlling the impres- 30 stamp operating means which is operated by a sion taking means or platen.

relatively light spring and restored by a solenoid The printing wheels have been generally inor electromagnet, the control of the solenoid dicated in Fig. 1 by a broken line circle Hi. The or magnet being of an interlocking nature such frame I2, the side frames (not shown) supportas to insure that the operating means is fully ing the printing head, and the two-part housrestored before a second operation can take ing l3, M, are so disposed as to provide a deep 35 place. unobstructed opening I! to receive the papers Another specific object is to provide a time to be stamped. stamp operating mechanism which is spring- The impression taking means may consist of operated and controlled by two interlocked solea platen l8- of resilient material mounted on a 49 noids or electromagnets in such fashion as to plate I9 which is recessed to receive the platen make said mechanism absolutely reliable in its as shown. in Fig. 3. The frame l2 beneath the action and more or less independent of variaprinting wheels I6 is provided with a rectangutions in potential of the current supply line. lar opening 20 in which the platen Wand its A further specific object is to provide controlsupporting plate H; are free to move vertically ling mechanism for time stamps which is adaptto project a paper resting on the platen against 5 ed. to be controlled by either the insertion of the the printing wheels H5 in the usual manner. The paper to be stamped or by the pressure of the plate is is adjustably secured, as by screws 2|, operators fingers. 22, to a frame 23 (Figs. 1 and 3) shaped like an Still another specific object is to provide a inverted U and composed of sheet metal, the

time stamp controlling mechanism in. which plate 59 being secured to the. upper horizontal 50 provision is made. for preventing unwanted repart of the frame. The side members of the peated impressions. frame 23 are slotted. as at 24 to embrace studs Various other objects, advantages, and fea- 25 each. riveted to the inside of one of the vertures of the present invention will be specifically tical members of a U-shaped sheet metal subpointed out in the following description and frame 26 secured to the base III as by screws 21. 55

Tie bolts 28 and spacing bushings 29, connecting the upper ends of the frame 26, have the double purpose of guiding the frame 23 in its vertical movements and rigidly securing the upper ends of frame 26 in spaced relationship.

Adjacent each vertical member of frame 23 is a toggle comprising a pair of links 30, 3| the upper ends of links 33 being pivoted to the frame 23 as at 32 and the lower ends of links 3i being pivoted to the studs 25. The pairs of links 33, 3| are pivotally joined together by a short.

shaft 33 which passes through a bushing 34 holding the two pairs of links in spaced relationship as shown in Fig. 1. It is fairly obvious that straightening of the two toggles comprising the links 30, 3| will ultimately result in the platen being moved upwardly toward the printing wheels I6.

The straightening of the toggles is effected by means of a spring 35 anchored to a stud 36 carried by the frame i2 and to a stud 31 secured to a member 38 rigidly mounted on a shaft 39 journalled in frame 26. The member 38 is slotted to embrace an enlargement of the bushing 34, the slot being wide enough to allow a certain amount of looseness or lost motion between member 38 and the enlargement of bushing 34, as shown in Fig. 3. The member 38 has a downwardly projecting arm 40 to which is pivoted one link 4| of a toggle comprising links 4|, 42. The link 42 is pivoted at its left-hand end (Fig. 3) 'to link and at its right-hand end to a bracket 43 secured to frame 26. When the parts are in the position of Fig. 3, a bent-over lug 44 formed in link 42, is engaged by a shoulder in a latch arm 45 secured to a short shaft 46 which is journalled in frame 26. Fig. 3 shows the normal position of the parts in which the toggles comprising links 33, 3|, are fully bent so that the frame 23 is freely resting on studs 25, and platen I8 is flush with the edges of opening 20, permitting a'paper to be freely inserted in the opening H in readiness for the stamping operation. In this position of frame 23, the spring 35 tends to rock member 38 in a counterclockwise direction to bend the partially bent toggle comprising links 4|, 42 but such action is prevented by latch arm 45.

The latch arm 45 is operated by means of a solenoid 41 (Fig. 2) carried by a frame 48 which is secured to the base It in front of frame 26. The plunger 49 of solenoid 41 is pivoted at 5!) to an arm 5| secured to a short shaft 52 journalled in frame 26. Rearwardly of the frame 26 (Fig. 3) the shaft 52 has secured thereto an arm 53 which is connected by a link 54 to an arm 55 secured to the shaft 45 carrying the latch arm 45. t is plain that energization of solenoid 4'! will rock arm 5| and shafts 52, 46 in a clockwise direction through the connections 53, 54, 55, thus disengaging the shoulder in latch arm 45 from bent-over lug 44.

The member 38 will now be free to rock in a counterclockwise direction under the influence of spring 35 thus forcing shaft 33 to the left, after a slight preliminary movement to take up the lost motion, (Fig. 3) straightening the toggles 30, 3| and forcing the platen I3 upwardly toward type wheels l6.

The parts are restored to the position of Fig. 3 by means of a solenoid 55 (Figs. 1 and 4) mounted to the right of the frame 26 (Fig. 1) The solenoid 5G comprises an inverted U-shaped frame 51 of magnetic material secured to a relatively thick rectangular block 58 also of magnetic material and rigidly mounted on lugs 59 formed in the base If). The block 58 is provided with a circular opening 63 which acts as a guide for the plunger 3| of the solenoid, which plunger normally rests on a resilient cushion 52 secured to the base It as shown in Fig. 4;. Both the plunger El and the block 58 have slots or recesses 63 and 64, which coact to form a relatively long recess. The shaft 39 extends rearwardly through a hole in block 58 (Fig. 3) and the recess 64 where an arm 65 is secured to said shaft as shown in Fig. 4. The arm 65 extends into the recess 63v and is adapted to be engaged by a short pin 66 carried by plunger 6|.

When the spring35 is effective to straighten the toggles 30, 3| and move the platen upwardly, the shaft 39 will rock counterclockwise (Fig. 4) and arm 65 will move to the position shown by broken lines in Fig. l thus preventing further movement of the member 38. This will occur just before the platen forces the paper to be stamped against the printing wheels l6 but the looseness of the slot inmember 38 will permit the momentum of the platen to convey the latter further upwardly a slight amount thus causing the impression to be made by a sharp blow of the platen rather than by a steady pressure of relatively longer duration. This mode of operation also prevents wedging the paper to be stamped in case the platen is not retracted properly, as, after such a blow, the platen and frame 23 will fall an amount sufficient to again take up the slack in the connection to member 38 thus releasing the paper in readiness for removal.

After each printing operation the solenoid is energized in a manner hereinafter to be described, causing plunger 6! to move upwardly, rocking shaft 39 in a clockwise direction due to the coaction between pin 66 and arm 35, thus drawing toggle 4|, 42 back to the slightly bent position of Fig. 3 where the shoulder in latch arm 45 will reengage lug 44, being drawn to that position by the action of a spring 61 anchored to arm 53 and to a stud carried by frame 25 (Fig. 3).

The construction just described has a number of important features of improvement. One of these features is the use of toggles which permits using a spring for operating the platen, the operating force of which spring may be very weak in comparison to the force required to opcrate the platen by direct action. It is quite obvious from Fig. 3 that a small force applied to the common pivots of the toggles 39, 3| in a direction transverse to the line of action of the platen l8 produces a much greater force on the line of action of the platen. This force becomes greater as the toggles are straightened out and, as the movement produced by spring 35 is extremely rapid, it is plain that the relatively weak spring produces quite a large force of impact of the platen against the type wheels. This feature is especially important in time stamps of the type described in the above patent as, in addition to the six of more type wheels necessary to print the time, day of month, year, and so on,

solenoid, the impression of the type was not always even and sharp.

Another feature is that the operation of the time stamp is more reliable when alternating current must be used to operate thetimeistamp, since the impact of the platen is always uniform, being due to spring action rather than subject to the uncertain action of the alternating current which is notoriously unreliable for operation of magnets and solenoids.

As an example, if, as sometimes happens in former machines, the contacts controlling the operation of the solenoid or magnet producing the impact of the platen came after the peak point of :the alternating current wave, the force of impact would be sluggish and weaker than if closure occurred at or slightly prior to the peak point. This is undesirable since it is important that the initial movement of the platen be as rapid as possible in order to gain suificient momentum in the short distance the platen travels under the direct action of the magnet or solenoid to ensure completion of the stroke by the momentum permitted by the usual lost motion of the parts connecting the platen and its operating solenoid or magnet. With the present construction the main solenoid 56 merely restores the platen, and the solenoid 41, being small and having no heavy work to perform can operate very quickly. Obviously, only a very small force is required to keep the toggle 4|,- 42 in the nearly straight position of Fig. 3 and hence the pressure on latch 45 is very small permitting the use of a small quick acting solenoid to release the latch. Indeed, as constructed, a very light pressure of a finger on the end of plunger 49 is amply suflicient to release the latch arm 45, nevertheless, the operation of the platen is extremely rapid and a clear, uniform impression is always obtained irrespective of the point in the alternating current wave at which solenoid 41 is energized.

As will now be explained in detail, the control of. the main solenoid 56 is of an interlocking nature such that current suflicient to fully restore the platen is always obtained. Since the only requirement for successful operation is the {restoration of the platen as quickly as possible,

it' is unimportant if the solenoid 56 does not initially move the platen at a high rate of speed provided suflicient current passes through the solenoid to fully restore the platen.

The energization of the solenoid 41 may be effected by pressure of a finger on a button 68 (Fig. 1) secured to a short plunger 69 slidably mounted in a guide bushing 78 carried by the upper half I4 of the housing.

The right-hand or rear end (Fig. 1) of plunger 68 is in position to engage a bent over lug 'II formed in a link I2 whose left end in said figure is slidably mounted upon a slot in a bracket I3 secured to the frame carrying the printing wheels I6. A leaf spring catch 14 secured to bracket 13, normally overhangs and holds the link I2 in the slot in the bracket I3 but permits removal of the linkwhen making repairs, replacements, or adjustments. The right-hand .end of link I2 is pivoted at I5 to a vertically extending lever I8 pivoted at IT to the frame 51 of solenoid 58. Normally a spring I8, anchored to a pin I8 on frame 51 and to a flange 88 formed in lever "I6, holds the parts in the position of .Fig. 1 with a lug 8| offset from link 12 abutting bracket "I3. The flange 88 is slotted to support a link 82 which is pivoted at 83 to a rectangular block 85.

The block 85 is pivotally mounted on a rod 88 journalled in a bracket 81 secured to the frame I2. A T-shaped'contact member 88 is mounted on and insulated from the block 85 and extends downwardly between a front pair of contacts 89 (Fig. 5) and a rear pair of contacts 88 (Fig. I) mounted on opposite sides of a rectangular block 8| of insulating material secured to the base I8. The construction is such that the T-shaped contact member 88 bridges contacts 88 in the position of Fig. 1 and bridges contacts 88 when block 85 is moved a slight amount counterclockwise. Normally a spring 82 anchored to link 82' and to the flange 88 in lever 16, holds the block 85 and link 82 in the position of Fig. 1 with contact member 88 bridging contacts 88. In this position of the parts, a lug 83 formed in link 82 is slightly to the right (Fig. 1) of the flange 88. When button 68 is pressed to the right (Fig. 1) by the operator, the link 12 will be likewise moved to the right rocking lever I6 clockwise. The flange 88 will then engage the lug 83 and force link 82 to the right thereby rocking block 85 and contact member 88 in a counterclockwise direction to bridge contacts 88. As will 'be seen in Fig. 8, this operation energizes the solenoid 41 and the printing operation takes place as described above.

Energization of solenoid 56 to cause the restoration of the platen I8 to normal position is accomplished by the upward movement of platen I8. Pivoted at 94 to the frame supporting printing wheels I6 is a lever 85 having at its front or right-hand end (Fig. 1) an offset lug 86 in the path of movement of the platen. The lever 85 is bent to a U-shape at its rear end, in order to avoid striking parts of the frame and certain mechanism not shown, and is connected by a vertical link 87 to an arm 88016 a bracket secured to the front face of a block 98 pivotally mounted on rod 86 (see Figs. 5 and 6 also). The block 88 may be exactly like the block 85 if desired, and like the latter, may have secured thereto a T-shaped contact member I88 coacting with a pair of contacts I8I like contacts 88. A spring I82 anchored to the base I 8 and to a bracket secured to block 88, as by, one of the screws receiving member I88 to the said block, normally holds the parts in the positions of Figs. 1 and 6 wherein the contacts I8! are not bridged. A slotted plate I83 is also secured to block 98 as by the same screws which secure bracket 88 to said block (Fig. 5), and into the slot in said plate extends a latch I84 pivotally connected to the frame 5'! on the left-hand side thereof (Fig. 4), the latch being suitably bent to permit such connection. The latch I84 is urged downwardly by a spring I85 and normally rests at the bottom of the slot in plate I83 with a latching shoulder I86 formed in the latch occupying a position slightly rearwardly or to the left (Fig. 6) of the plate I 83.

The shaft 38 is extended to the rear of the solenoid 56 beneath the latch I84 and has secured thereto an arm I81 having a pin and slot connection to a link I88 pivoted to arm 88 at the point Where link 87 is pivoted. When the parts are in the normal position of Fig. 5, movement of the member I88 to bridge contacts I 81 is positively prevented by the pressure of the pin or arm ID! at the upper end of the slot in link I88. The arm I81 has abent-over lug I88 in the plane of a rock lever III! loosely pivoted on shaft 39. The left-hand end of this rock lever has secured thereto a block III extending upwardly beneath the latch I04.

The other arm of the lever H extends tothe right beneath the link 82. Normally a spring I I2 holds the rock lever in the position of Fig. where it rests on lug I09.

When the button 68 is pressed to energize solenoid 41, the latter will cause the platen I8 to be operated as described. The shaft 39 will e rocked in a counterclockwise direction (Fig. 5) as the platen moves upwardly and the rock lever H0 willfoilow due to the effect of spring H2. The right-hand end of lever H0 will then lift the link 82 enough to disengage lug 93 from the flange 85 whereupon spring 92 (Fig. 1) will draw the link 82 to the left. As a consequence of this movement of link 82, contacts 89 will again be bridged by contact number 88 and the circuit through contacts 90 will be broken.

7 During the counterclockwise movement of lever Hi? the pin on arm I01 will move downwardly in the slot in link I58 and the block I II will also move downwardly to permit latch I04 to drop at the proper time. Near the end of the upward movement of the platen the latter will engage the lug 96 (Fig. i) and rock lever 95 in a clockwise direction thus moving link 92' downwardly and rocking arm 98 and block counterclockwise (Fig. 6) causing bridging of contacts IGI by number IGE. The plate I93 will move with block 99 with the result that the shoulder I06 in latch I64 will get in front of said plate and permit latch E04 to drop slightly thus holding the block 99 and member I99 in shifted position with contacts IGI bridged by said member.

Since contacts 89 have also been caused to reclose by the initial movement of lever I I0, at the end of the upward stroke of the platen the solenoid 56 will be energized and will eifect restoration of the platen and its operating mechanism to starting position as described. During the restoration of the platen, shaft 39 will be rocked in a clockwise direction causingv similar movement or" lever H5 allowing link 82 to drop to the position of Fig. 1.

During the last part of the return movement of lever Hi), the block ill will strike latch Hi4 and raise it sufficiently to disengage shoulder I06 from plate H33 and permit bl ck 99, plate i523, and member I06 to return to the position of Fig. 6, under the influence of spring I32, thus interrupting I the. circuit through contacts IBI.

Link i953 prevents the member $09 from bridging contacts I iii when the platen I8 is in its normal position and also operates to positively move member H153 to the position of Fig. 6, thus counteracting possible sticking of the contacts or failure of the spring It? to return the parts to normal position. The lifting of link 82 prevents a second operation of the time stamp unless the button 68 is released as the contacts 90 can not be again bridged by member 88 until the button 68 has been released to permit link 82 and lever 76 to resume their normal positions with lug 93 in the rear of flange 86.

Fig. 7 illustrates a modification wherein the operation of the time stamp is directly initiated by the paper to be stamped. V The lever I6 is replaced by a short lever 16a which is shaped very much like the lower half of leverl6, having a flange 89a like the flange 88, and is pivoted at 'I'Ia. A spring 18a holds the lever in the position of Fig. 7 wherein the upperend of lever 161;

abuts the forward end of a suitable slot cut in frame I2 and also projects into the opening I'I. When the paper to be stamped is pushed into the opening I1, the rear edge of said paper will strike theupper end of lever 16a and rock it clockwise a distance sulficient to cause member 88 to bridge contacts 90 through the action of link 82 as previously described. It is preferable that in this case the springs connected to link 82 and lever 16a. be as light as possible to prevent the papers inserted in opening II from buckling against lever 16a without operating the latch.

While there has been shown and described and pointed out the fundamental novel features of the invention as applied to a single modification, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention therefore to be limited only as indicated by the scope of the following claims.

What is claimed is as follows:

1. In a time stamp, an impression element, toggle means connected to said element and adapted when straightened to operate said element to take an impression, a spring having a tendency to straighten the toggle means, means normally holding the toggle means in bent position, and a device for releasing the last named means to permit the spring to straighten the toggle and operate the impression element.

2. In a time stamp, an impression member, a pair of toggles connected to the impression member and adapted to be straightened to operate the impression member to take an impression, a member for straightening the toggles, a spring for operating said member. a latch for restraining said member and its spring against operation, and an electromechanical device for releasing the latch to permit an operation of said member.

7 3. In a time stamp, an impression element, a

toggle connected to the impression element and adapted to be straightened to operate the impression element, a member having a lost motion connection to the first named toggle for straightening the latter, a spring connected to said member and normally tending to operate the later to straighten thefirst named toggle, a second toggle connected to said member and adapted when partially bent to prevent said member from straightening the first toggle, means for holding the second toggle in partially bent position, and an electromechanical device for releasing the last named means whereby to permit the second toggle to bend a further extent. 1

4. Ina time stamp, an impression element, a light spring, means adapted to be operated by the light spring for operating the impression taking element; and releasable means for restraining the spring against operation including a partially bent toggle and a latch holding the toggle in' partially bent position.

5. In a time stamp, an impression element, toggle means connected to said element and adapted when straightened to operate said element to take an impression, a springhaving a tendency to straighten the toggle means, means normally holding the toggle means in bent position, a device for releasing the last named means to permit the spring to bend the toggle and operate the impression element, an electrpmechanical device for bending the toggle means to restore the impression element, and means operated by the impression element for initiating operation of the electromechanical means after an impression has been taken.

6. In a time stamp, an impression member, a pair of toggles connected to the impression member and adapted to be straightened to operate the impression member to take an impression, a member for straightening the toggles, a spring for operating said member, a latch for restraining said member and its spring against operation, an electromechanical device for releasing the latch to permit an operation of said member, means for restoring and relatching said member, and means connected to said member for preventing a second operation of the electromechanical device before said member has been relatched.

7. In a time stamp, an impression element, toggle means connected to said element and adapted when straightened to operate said element to take an impression, a spring having a tendency to straighten the toggle means, means normally holding the toggle means in bent po-. sition, a device for releasing the last named means to permit the spring to straighten the toggle and operate the impression element, means for bending the toggle to restore the latter to normal bent position, and means connected to said toggle for preventing a second operation of said device before the toggle is fully restored to bent position.

8. In a time stamp, an impression element, a light spring, means adapted to be operated by the light spring for operating the impression taking element, releasable means for restraining the spring against operation including a partially bent toggle and a latch holding the toggle in partially bent position, a low power solenoid for operating said latch to release the toggle, a relatively higher power solenoid for restoring the impression element against the tension of said spring, and means connected to the toggle for preventing a second operation of the first named solenoid before the second named solenoid has fully restored the impression element.

9. In a time stamp, an impression element, a light spring, means adapted to be operated by the light spring for operating the impression taking element; releasable means for restraining the spring against operation including a partially bent toggle and a latch holding the toggle in partially bent position, a solenoid for operating said latch to release the toggle, a circuit for controlling said solenoid, a second solenoid for restoring the togggle to latching position, means controlled by the impression element for energizing the second solenoid, and means in said circuit and controlled by movement of the toggle for preventing a second operation of the first solenoid before the second solenoid has restored the toggle to latching position.

10. In a time stamp, an impression element, toggle means connected to said element and adapted to be straightened to operate the impression element to take an impression, means tending to straighten the toggle means, means preventing straightening of the toggle means, an electromechanical device for operating the preventing means to release said toggle for an operation, means for bending the toggle to restore the latter and impression element to normal position, an electric circuit for controlling said device, and means in said circuit controlled by movement of the toggle for preventing a second operation of the electromechanical device before the toggle and impression element are fully restored.

11. In a time stamp, an impression element, a light spring, means adapted to be operated by the light spring for operating the impression taking element; releasable means for restraining the spring against operation including a partially bent toggle and a latch holding the toggle in partially bent position, a solenoid for operating the retaining means to release the operating means, a circuit for controlling said solenoid, contacts in said circuit, means for operating said contacts to close the circuit and adapted to be disconnected from said contacts to permit the latter to reopen, means for restoring the impression element and its operating means, and means operated by the impression element for disconnecting the contact op erating means.

12. In a time stamp, a printing element, an impression element coacting therewith, toggle mechanism connected to the impression element, means normally tending to straighten the toggle and mechanism and thereby operate the impression means to take an impression from the printing element, means for holding the toggle mechanism in bent position, and a trip device for releasing the holding means, said device being actuated by a paper to be stamped when placed in position between the impression element and printing element.

13. In a time stamp, a printing element, an impression element co-operating therewith, a toggle device connected to the impression means and adapted when straightened to move the impression element toward the printing element to take an impression, means normally tending to straighten the. toggle, releasable means normally holding the toggle device in bent position, means for releasing the holding means, and a normally ineifective retracting device for the toggle device automatically rendered effective by movement of the impression element during its impression taking stroke.

14. In a time stamp, a printing element, an impression element co-operating therewith, a toggle device connected to the impression means and adapted when straightened to move the impression element toward the printing element to take an impression, means normally tending to straighten the toggle, releasable means normally holding the toggle device in bent position, means for releasing the holding means, a normally ineffective retracting device for the toggle device automatically rendered effective by movement of the impression element during its impression taking stroke, and means for preventing a second operation of the releasable means before the toggle device is fully retracted.

' CLAIR D. LAKE. 

